The invention relates to a road marking unit comprising a housing with a light-transmitting window. The invention also relates to a road marking system.
Such a road marking system is known from GB 2 159 559. In the known road marking unit, light waveguides constructed as glass fibers are provided in the housing, first ends of said waveguides being directed towards the window and second ends thereof being optically coupled to a light source or to a reflector. Such a road marking unit may serve to distinguish individual driving lanes of a road from one another. It is desirable to have a possibility to render the road marking unit visible or invisible in dependence on the ambient conditions. The known road marking unit, in which the second ends of the light waveguides are coupled to a light source, can be made visible or invisible in the case of weak ambient light in that the light source is switched on or off. During the day, in particular in direct sunlight, however, the ambient light is so strong that it drowns out the light originating from the road marking unit. It is not possible then to influence the visibility of the road marking unit.